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Logging

Why, What & How we Log

Description

The npm CLI has various mechanisms for showing different levels of information back to end-users for certain commands, configurations & environments.

Setting Log Levels

loglevel

loglevel is a global argument/config that can be set to determine the type of information to be displayed.

The default value of loglevel is "notice" but there are several levels/types of logs available, including:

  • "silent"
  • "error"
  • "warn"
  • "notice"
  • "http"
  • "timing"
  • "info"
  • "verbose"
  • "silly"

All logs pertaining to a level proceeding the current setting will be shown.

All logs are written to a debug log, with the path to that file printed if the execution of a command fails.

Aliases

The log levels listed above have various corresponding aliases, including:

  • -d: --loglevel info
  • --dd: --loglevel verbose
  • --verbose: --loglevel verbose
  • --ddd: --loglevel silly
  • -q: --loglevel warn
  • --quiet: --loglevel warn
  • -s: --loglevel silent
  • --silent: --loglevel silent

foreground-scripts

The npm CLI began hiding the output of lifecycle scripts for npm install as of v7. Notably, this means you will not see logs/output from packages that may be using "install scripts" to display information back to you or from your own project's scripts defined in package.json. If you'd like to change this behavior & log this output you can set foreground-scripts to true.

Registry Response Headers

npm-notice

The npm CLI reads from & logs any npm-notice headers that are returned from the configured registry. This mechanism can be used by third-party registries to provide useful information when network-dependent requests occur.

This header is not cached, and will not be logged if the request is served from the cache.

See also